FIG. 1 depicts an air-bearing surface (ABS) view of a read transducer used in magnetic recording technology applications. The read transducer 10 includes shields 12 and 18, insulator 14, side magnetic bias structures 16, and sensor 20. The read sensor 20 shown is a dual free layer sensor. In other cases, the read sensor 20 is a giant magnetoresistive (GMR) sensor or tunneling magnetoresistive (TMR) sensor. In such cases, the read sensor 20 may include an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. Capping and seed layer(s) may also be used. The free layer has a magnetization sensitive to an external magnetic field. Thus, the free layer functions as a sensor layer for the magnetoresistive sensor 20. If the sensor 20 is to be used in a current perpendicular to plane (CPP) configuration, then current is driven in a direction substantially perpendicular to the plane of the layers. Conversely, in a current-in-plane (CIP) configuration, then conductive leads (not shown) would be provided on the magnetic bias structures 16.
FIG. 2 depicts a method for providing the transducer 10. Referring to FIGS. 1 and 2, the sensor stack is deposited, via step 52. Thus, the layers for the sensor 20 are provided. The read sensor 20 is defined in the track width direction. The track width direction is otherwise known as the cross-track direction. Thus, the sidewalls and track width, TW, of the sensor 20 are formed. The side bias structures 16 are then provided, via step 56. Step 56 may include depositing the insulator 14 and forming the bias structures 16.
After the side bias structures 14 are formed, the read sensor 20 is then defined in the stripe height direction, via step 58. Thus, the stripe height, SH, of the sensor 20 is set. If a dual free layer sensor 20 is to be fabricated, then a rear bias structure (not shown in FIG. 1) is then provided, via step 60. Step 60 includes depositing the magnetic materials for the rear bias structure. This is typically carried out while the mask used for step 58 is in place.
After step 60 is performed, an aluminum oxide refill layer and metal chemical mechanical planarization (CMP) stop layer are deposited, via step 62. The mask used for step 58 is then desired to be removed and a flat surface provided for subsequent processing. Thus, a mill open and CMP process are performed, via step 64. The mill open ion mills the transducer 10 at a high angle from normal to the surface of the transducer. Thus, the material(s) on the side of the mask used for step 58 are removed. The mask may then be lifted off and a CMP performed. The CMP stops on the metal CMP stop layer. Without the CMP stop layer, the aluminum oxide has a high removal rate on the order of 0.1-0.3 microns per minute. Thus, as long as the metal CMP stop layer is used, a flat surface may be provided while protecting the rear bias and other structures from damage.
Although the conventional method functions, there may be drawbacks. Accordingly, what is needed is an improve method for fabricating a magnetic recording read transducer.